Mitochondrial proteases and their roles in mitophagy in plants, animals, and yeast

Mitochondria play a central role in cellular respiration and other essential metabolic and signaling pathways. To function properly, mitochondria require the maintenance of proteostasis-a balance between protein synthesis and degradation. This balance is achieved through the mitochondrial protein quality control (mtPQC) system, which includes mitochondrial proteases and mitophagy. Mitochondrial proteases ensure proper protein sorting within the mitochondria and maintain proteome homeostasis by degrading unassembled, damaged, or short-lived regulatory proteins. Numerous studies have demonstrated the critical role of mitochondrial proteases in regulating mitophagy-the selective degradation of damaged, aging, or excess mitochondria or their fragments via autophagy. Notably, the rhomboid PARL protease is involved in ubiquitin-dependent PINK1-Parkin mitophagy in mammals, while the i-AAA protease Yme1 plays a role in mitophagy in budding yeast. Despite the conservation of core autophagy genes, knowledge about the molecular mechanisms and protein regulators of mitophagy in plants remains limited. In this review, we discuss recent advances in understanding the roles of mitochondrial proteases and mitophagy across plants, animals, and yeast. By comparing these mechanisms across kingdoms, we highlight the potential regulatory function of the plant i-AAA mitochondrial protease in controlling mitophagy, providing new insights into mtPQC networks in plants.